| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens of which the temperature characteristic and the wavelength characteristic become compatible in a good state, especially, an objective lens made to cope with writing to an optical information recording medium, and to provide an optical pickup device, and an optical information recording and reproducing device. <P>SOLUTION: The objective lens of this invention has an image-forming magnification to a luminous flux of a wavelength λ1 satisfying -1/4<m1<-1/15. Also, the objective lens is formed with a phase difference adding structure for giving a phase difference to at least one of the luminous fluxes of the wavelengths λ1, λ2 are formed, and is provided with a concentric central area including the optical axis and a peripheral area covering this central area. Then, the luminous flux of the wavelength λ2 passing through the peripheral area is not converged on the information recording surface of a 2nd optical information recording medium but becomes flare light. And, a concentric inner diameter centering the optical axis formed on the information recording surface of the 2nd optical information recording medium by the flare light is 5-100 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
